Needle electrode assembly for electroporation mediated delivery of genes and drugs

ABSTRACT

A method for in vivo electrotherapy, or electroporation-mediated therapy, using a needle array apparatus is provided. Treatment of tumors with a combination of electroporation using the apparatus of the invention, and a chemotherapeutic agent, caused regression of tumors in vivo.

REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of application Ser. No.09/427,151 filed Oct. 25, 1999 now which is a continuation ofapplication Ser. No. 08/537,265 filed Sep. 29, 1995 now U.S. Pat. No.5,993,434, which is a Continuation-in-Part of application Ser. No.08/467,566, filed on Jun. 6, 1995 now U.S. Pat. No. 5,702,359, which isa Continuation-in-Part of application Ser. No. 08/042,039 filed on Apr.1, 1993 now U.S. Pat. No. 5,439,440.

BACKGROUND OF THE INVENTION

The present invention relates to the treatment of ailments in humans andother mammals, and more particularly, to an improved method andapparatus for the application of controlled electric fields for in vivodelivery of genes and pharmaceutical compounds into live cells of apatient by electroporation.

In the 1970's it was discovered that electric fields could be used tocreate pores in cells without causing permanent damage to them. Thisdiscovery made possible the insertion of large molecules into cellcytoplasm. It is known that genes and other molecules such aspharmacological compounds can be incorporated into live cells through aprocess known as electroporation. The genes or other molecules are mixedwith the Eve cells in a buffer medium and short pulses of high electricfields are applied. The cell membranes are transiently made porous andthe genes or molecules enter the cells. There they can modify the genomeof the cell.

Electroporation has been recently suggested as one approach to thetreatment of certain diseases such as cancer. For example, in thetreatment of certain types of cancer with chemotherapy it is necessaryto use a high enough dose of a drug to kill the cancer cells withoutkilling an unacceptable high number of normal cells. If the chemotherapydrug could be inserted directly inside the cancer cells, this objectivecould be achieved. Some of the best anti-cancer drugs; for example,bleomycin, normally cannot penetrate the membranes of certain cancercells. However, electroporation makes it possible to insert thebleomycin into the cells.

One therapeutic application of electroporation is for cancer treatment.Experiments on laboratory mammals have been carried out and reported asfollows: Okino, M., E. Kensuke, 1990. The Effects of a Single HighVoltage Electrical Stimulation with an Anticancer Drug on in vivoGrowing Malignant Tumors. Jap. Journal of Surgery. 20: 197-204. Mir, L.M., S. Orlowsid, J. Belehradek Jr., and C. Paoletti. 1991.Electrochemotherapy Potentiation of Antitumor Effect of Bleomycin byLocal Electric Pulses. Eur. J. Cancer. 27: 68-72. Clinical trials havebeen conducted and reported by Mir, L. M., M. Belehradek, C. Domenge, S.Orlowski, B. Poddevin, et al. 1991. Electrochemotherapy, a novelantitumor treatment: first clinical trial. C. R. Acad. Sci. Paris.313:613-618.

This treatment is carried out by infusing an anticancer drug directlyinto the tumor and applying an electric field to the tumor between apair of electrodes. The field strength must be adjusted reasonablyaccurately so that electroporation of the cells of the tumor occurswithout damage, or at least minimal damage, to any normal or healthycells. This can normally be easily carried out with external tumors byapplying the electrodes to opposite sides of the tumor so that theelectric field is between the electrodes. The distance between theelectrodes can then be measured and a suitable voltage according to theformula E=V/d can then be applied to the electrodes (E=electric fieldstrength in V/cm; V=voltage in volts; and d=distance in cm). Wheninternal tumors are to be treated, it is not easy to properly locateelectrodes and measure the distance between them. In the aforementionedparent application, there is disclosed a system of electrodes for invivo electroporation wherein the electrodes may be inserted into bodycavities. In a related U. S. Pat. No. 5,273,25 a syringe for injectingmolecules and macromolecules for electroporation utilizes needles forinjection which also function as electrodes. This construction enablesthe subsurface placement of electrodes. It would be desirable to have anelectrode apparatus having electrodes that can be inserted into oradjacent tumors so that predetermined electric fields can be generatedin the tissue for electroporation of the cells of the tumor.

Studies have also shown that large size nucleotide sequences (up to 630kb) can be introduced into mammalian cells via electroporation (Eanault,et al., Gene (Amsterdam), 144(2):205, 1994; Nucleic Acids Research,15(3):1311, 1987; Knutson, et al., Anal. Biochem., 164:44, 1987; Gibson,et al., EMBO J., 6(8):2457, 1987; Dower, et al., Genetic Engineering,12:275, 1990; Mozo, et al., Plant Molecular Biology, 16:917, 1991),thereby affording an efficient method of gene therapy, for example.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to providean improved apparatus that can be conveniently and effectivelypositioned to generate predetermined electric fields in pre-selectedtissue.

It is another principal object of the present invention to provide animproved apparatus that provides an effective and convenient means forpositioning electrodes into tissue for the injection of therapeuticcompounds into the tissue and application of electric fields to thetissue.

In accordance with a primary aspect of the present invention anelectrode apparatus for the application of electroporation to a portionof the body of a patient, comprises a support member, a plurality ofneedle electrodes adjustably mounted on said support member forinsertion into tissue at selected positions and distances from oneanother, and means including a signal generator responsive to saiddistance signal for applying an electric signal to the electrodesproportionate to the distance between said electrodes for generating anelectric field of a predetermined strength.

Another aspect of the invention includes needles that function forinjection of therapeutic substances into tissue and function aselectrodes for generating electric fields for portion of cells of thetissue.

In yet another aspect of the invention is provided a therapeutic methodutilizing the needle array apparatus for the treatment of cells,particularly tumor cells.

BRIEF DESCRIPTION OF TEE DRAWINGS

FIG. 1 is a side elevation view, in section of a needle assembly inaccordance with a preferred embodiment of the invention.

FIG. 2 is a bottom view of the embodiment of FIG. 1.

FIG. 3 is an assembly drawing showing a perspective view of an alternateembodiment of the invention.

FIG. 4 is a perspective view of the embodiment of FIG. 3 shownassembled.

FIG. 5 is a perspective view of a selector switch for the electrodeassembly of FIG. 4.

FIGS. 6a-6 c is a diagrammatic illustration of selected contactpositions of the switch of FIG. 5.

FIG. 7 is a perspective view of a further embodiment of the invention.

FIG. 8 is a perspective view of a still further embodiment of theinvention.

FIGS. 9a-9 d is a top plan view, illustrating a preferred form ofelectrodes and sequence of use.

FIGS. 10a and 10 b show the tumor volume after 43 days of ECT withbleomycin in Panc-3 xenografted nude mice.

(D=drug; E=electroporation)

FIG. 11 is an illustration of tumor growth of Panc-3 cells after ECTwith bleomycin in nude mice.

FIGS. 12a and 12 b show the tumor volume after 20 and 34 days of ECTwith bleomycin, respectively, in non-small cell lung carcinoma (NSCLC)xenografted nude mice.

(D=drug; E=electroporation)

FIG. 13 shows the tumor volume after 34 days of ECT with bleomycin innon-small cell lung carcinoma (NSCLC) xenografted nude mice. The arrowindicates retreatment of one mouse at day 27. (D=drug;E=electroporation)

FIGS. 14a and 14 b show pre-pulse dosing with neocarcinostatin in Panc-3and NSCLC, respectively, in the nude mouse model.

FIGS. 14c and 14 d show post-pulse dosing with neocarcinostatin inPanc-3 in the nude mouse model.

DETAILED DESCRIPTION OF TEE PREFERRED EMBODIMENTS

As used herein the term “molecules” includes pharmacological agents,genes, antibodies or other proteins. One human therapeutic applicationof electroporation consists of infusion of an anticancer drug andelectroporation of the drug into the tumor by applying voltage pulsesbetween electrodes disposed on opposite sides of the tumor, calledelectrochemotherapy (ECT). The present invention was devised primarilyfor enabling ECT such as that reported by Okino and Mir et al to becarried out on non-surface tumors such as those inside the body.However, it may be utilized for other therapeutic applications.

Referring to FIG. 1 of the drawings, a needle assembly in accordancewith preferred embodiment of the invention is illustrated and designatedgenerally by the numeral 10. The needle assembly comprises an elongatedtubular support body 12 which is preferably in the form of a hollowstainless steel shaft. A center needle mount 14 is mounted on the lowerend of the shaft 12 and has a central bore 16 for receiving and guidinga center needle 18. The shaft 12 includes a needle exit slot 20 throughwhich the needle electrode 18 extends from the interior thereof to theexterior where it is secured by a clamp 22 to the outside of the tube12.

The upper end of the electrode 18 may be secured to a screw 24 forconnection to an electrical circuit. The lower end of the tubular holder12 includes threats 26 for threatably receiving a collar 28 for mountinga plurality of needles and a stop collar 30 for stopping or locking thecollar 28 in position.

A plurality of needles 32 are mounted in grooves 34 equally spacedaround the outer surface of the needle collar 28. This provides acircular array of equally spaced needles, eight in number in theillustrated embodiment. The needles are held in place by a band clamp36, having the ends clamped together by a screw or nut and bolt 38 whichalso serves as an electrical connection for the needles. The band clamp36 directly engages and holds the needles in place.

This electrode assembly is designed to apply electrical energy to livingtissue when the needles are inserted into the tissue. The center needle18 acts as one electrode, such as an anode or cathode, and the other orannular arrangement of needles 32 functions as the opposite electrode.All of these needles are held in fixed positions when the clamps areinstalled and secured. One or more of the needles may be cannular ortubular in form for injecting molecules of genes, pharmaceutical orother substances into the tissue.

In operation the center needle should be adjusted in order to achievethe desired tissue penetration. This is done by releasing the pressureof the center needle clamp 22 and sliding the center needle 18 outwardlyor inwardly, as seen in FIG. 1, so that it extends from the centerneedle guide 14 to desired penetration distance. The needle is thenclamped in position. Thereafter the annular needles 32 are adjusted toachieve the desired penetration into the tissue. This can beaccomplished by releasing the pressure of the band clamp 36 and slidingthe needles 32 into the desired position. Minor adjustments can also bemade by moving the needle collar 28 toward and away from the end of theshaft 12. A therapeutic substance may be injected into the tissuethrough one or more of these needles or by a separate means.

After all needles are adjusted to the proper penetration, the shaft 12is grasped and the needles are inserted into the tissue to the desireddepth. Thereafter, a suitable pulse generator is connected to theelectrode assembly and the appropriate voltage applied to theelectrodes. A suitable quantity of therapeutic substance such as genesor molecules of a suitable chemical or pharmaceutical for treatment ofthe tissue is injected into the tissue before the voltage is applied.

A modification to this electrode assembly could include a solidnon-penetrating electrode (not shown) in place of the center needle. Thenon-penetrating center electrode could be any suitable shape conductorsuch as a button or plate attached to the end of the shaft 12 to contactthe surface tissue. The annular needle arrangement would be adjusted topenetrate the tissue at the desired depth when the center electrode isresting on a tissue surface. Electrical energy would flow from thepenetrating needles through the tissue and to the central electrode onthe surface. These arrangements can be utilized to treat near surfacetumors where the circular array of electrodes are designed to encirclethe tumor. The central electrode is positioned such that the electricalenergy flows through the tumor to the central electrode.

Other advantages of this electrode assembly are that all needles 18 and32 can be independently adjusted to achieve the desired penetration. Theneedle 28 collar can also be adjusted to position it from the end of theshaft 12 so that insertion of the center and annular needles can bedirectly observed. In addition, the needle collar 28 can have any sizeor configuration to encircle the tissue area to be treated.

Referring to FIGS. 3 and 4 an alternate embodiment of a circular arrayneedle electrode assembly is illustrated and designated generally by thenumeral 40. This needle assembly comprises a circular array of needles42 through 52, which are mounted in equally spaced relation in a hub 54mounted on an elongated cylindrical shaft 56. The hub 54 is preferablyof a suitably selected diameter to provide the desired diameter of thearrays to position around a tumor or other tissue to be treated. One ormore of the needles may be hollow to enable the injection of moleculesof a therapeutic substance, as will be more fully described hereinafter.

An electrical connector socket assembly comprises a body member 58having a central opening or bore 60 for receipt of shaft 56 and anannular array of a plurality of sockets 62 through 72 for receipt of theends of needles 42 through 52. The sockets 62 through 72 electricallyconnect the needles to leads 74 through 84 which connect to switchingmeans in the form of a distributing switch, as will be subsequentlydescribed.

The electrical connector socket 58 fits onto shaft 56 with the end ofthe needles extending into the electrical sockets 62 through 72 forconnecting to the leads 74 through 84. The shaft 56 which mounts theneedle array hub 54 and the socket assembly 58 mounts onto a holder 86adapted to be held in the hand. The holder 86 has an elongatedcylindrical configuration adapted to be held in the hand formanipulation. The holder 86 has a forward socket and including aforwardly extending tubular shaft 88 having a bore 90 into which shaft56 extends while the shaft 88 extends into a bore (not shown) within theconnector member 58. The shaft 56 extends into bore 90 and has a annulargroove or recess 92 which is engaged by a retainer latch which comprisesa transverse plug 94 in a bore 96 biased to one side and including abore 98 in which the annular slot 92 extends and is retained in theholder. A spring 102 mounted in bore 96 biases plug 94 to the latchedposition. The shaft 56 may be released for removal by pressing on end100 of plug 94.

The holder when assembled as shown in FIG. 4 may be grasped in the handand the needles inserted into a selected tissue area. The needles 42-52are preferably spaced and positioned to surround the selected tissue oftreatment. One or more of the needles 42-52, as previously explained,may be hollow to enable the injection of the desired therapeuticsubstance. The electrode leads 74-84 are then connected in a preferredarrangement to switch means such as a rotatable switch assembly, asshown in FIG. 5, which enables the selection of opposed pairs of theneedles for activation or the application of the electrical potential.

The switch assembly designated generally by the numeral 104 comprises astationary housing 106 which, in the illustrated embodiment, isgenerally cylindrical in configuration and in which is mounted a rotor108 with spaced contacts 110 and 112 connected by a pair of conductors114 and 116 to a pulse power generator 115. The rotor contacts 110 and112 are positioned within housing 106 to engage annular contacts 118,120, 122, 124, 126 and 128 to which leads 74-84 are connected.

Referring to FIGS. 6a, b and c, the rotor 108 has an internal portionhaving contacts 110 and 112 each of which bridge between two contacts118-128 to which the leads 74 through 84 are connected to connect thesource of power. The internal contacts 110 and 112 rotate with the rotor108 and can be selectively positioned in conductive relation with twoopposed pairs of the internal contacts 118-128 to thereby at the sametime activate two opposed pairs of the needle electrodes. This enablesthe operator to selectively position the electrodes surrounding aselected tissue and to selectively apply the direction of the electricalfield or electroporating voltage between two pairs of electrodes asdesired for optimum treatment. The rotor 108 enables the field to beselectively generated around or across the tissue from all directions.

Referring to FIG. 7 an alternate embodiment of an electric fieldgenerating array of parallel adjustably positionable electrodes, asdisclosed in the parent application, is illustrated. The electrodeassembly designated generally by the numeral 130 includes a pair ofspaced apart arrays 132 and 134 of conductive needle electrodes 136 and138 mounted on a dielectric carrier or support member 140. The needlearray 132 is held in a fixed clamp 142 which allows the needles 136 tobe adjusted in depth relative to the support 140.

The needles 138 are mounted in a moveable clamp 146 which is adjustablymounted on support member 140 by a clamp screw 148. The needles 136 and138 are each provided with a penetration stop 144. The gap spacing clampscrew 148 secures the clamp 146 in selected positions on the support140. A gap spacing sensor 150 senses the distance between the needlearrays 132 and 134 and generates a signal that is sent to the pulsegenerator via conductor cable 152. A pulse generator is connected to theneedle electrodes by means of cables 154 and 156.

Referring to FIG. 8, details of a needle holder or template for variousarrangements for establishing a spaced pair or parallel arrays ofneedles is illustrated. This embodiment comprises a base holder member158 having a plurality of adjacently positioned parallel slots 160 intowhich selected needles 162 and 164 may be positioned in selected spacedrelation. This holder may serve to mount a pair of oppositely polarizedneedle electrodes 162 and 164, as illustrated. These can be selectivelypositioned in selected space relationship to be disposed on oppositesides of a selected tissue. The needles are clamped into the slots by aclamp or plate 159. In addition, the holder may be used in combinationwith an additional holder for provision of multiple arrays on oppositesides of a selected tissue. The illustrated needles may be connected byconductors 166 and 168 to a suitable pulse generator.

Referring to FIGS. 9a through 9 d, an additional aspect of the inventionis illustrated. As more clearly illustrated, the combination electrodesmay take the form of separate needles 170 and 172 which may be firstinserted into or beside a selected tissue area such as on opposite sidesof a tumor 194 as illustrated. Thereafter the needles may be connectedto a syringe or other source of molecules and used to inject a selectedmolecular solution into the tissue area The needles may benon-conductive and a pair of electrodes 176 and 178, as illustrated inFIG. 9b, are selectively fed through the bore or lumen of the respectiveneedles into the tissue, as illustrated, and thereafter the needle isremoved, as shown in FIG. 9c. The electrodes 176 and 178 are eachprovided with an elongated insulated conductor 180 and 182 withconductive tips 184 and 186.

A pair of conductors 188 and 190 from a suitable power generator maythen be connected to the ends of the conductors of the electrodes bymicro clamps 192 and 194, as shown in 9 d, and an electric potentialapplied across the electrodes. This generates a field in the tissue andelectroporates the cells of the selected tissue, such as a tumor or thelike. This electroporation enables the selected molecules to enter thecells of the tissue and more efficiently kill or alter the cells asdesired. This form of needle and electrode may be used with any or allthe above described assemblies. It will be noted that in theaforementioned embodiments, when two pairs of electrodes are activatedat the same time, they are in a rectangular array.

These needle electrode assemblies, as above described, enable the invivo positioning of electrodes in or adjacent to subsurface tumors orother tissue. While the focus of the present application has been onelectrochemotherapy, the embodiment of the subject invention may beapplied to other treatments, such as gene therapy of certain organs ofthe body.

The nature of the electric field to be generated is determined by thenature of the tissue, the size of the selected tissue and its location.It is desirable that the field be as homogenous as possible and of thecorrect amplitude. Excessive field strength results in lysing of cells,whereas a low field strength results in reduced efficacy. The electrodesmay be mounted and manipulated in many ways including but not limited tothose in the parent application. The electrodes may be convenientlymanipulated on and by forceps to internal position.

The waveform of the electrical signal provided by the pulse generatorcan be an exponentially decaying pulse, a square pulse, a unipolaroscillating pulse train or a bipolar oscillating pulse train. Theelectric field strength can be 0.2 kV/cm to 20 kV/cm. The pulse lengthcan be ten μs to 100 ms. There can be one to one hundred pulses. Ofcourse, the waveform, electric field strength and pulse duration arealso dependent upon the type of cells and the type of molecules that areto enter the cells via electroporation.

The various parameters including electric field strengths required forthe electroporation of any known cell is generally available from themany research papers reporting on the subject, as well as from adatabase maintained by Genetronics, Inc., San Diego, Calif., assignee ofthe subject application. The electric fields needed for in vivo cellelectroporation, such as ECT, are similar in amplitude to the fieldsrequired for cells in vitro. These are in the range of from 100 V/cm toseveral kV/cm. This has been verified by the inventors own experimentsand those of others reported in scientific publications. The first invivo application of pulsed electric fields in the chemotherapy field totreat tumors was reported in 1987 by Okino in Japan.

Pulse generators for carrying out the procedures described herein areand have been available on the market for a number of years. Onesuitable signal generator is the ELECTRO CELL MANIPULATOR Model ECM 600commercially available from GENETRONICS, INC. of San Diego, Calif.,U.S.A The ECM 600 signal generator generates a pulse from the completedischarge of a capacitor which results in an exponentially decayingwaveform. The electric signal generated by this signal generator ischaracterized by a fast rise time and an exponential tail. In the signalgenerator, the electroporation pulse length is set by selecting one often timing resistors marked R1 through R10. They are active in both HighVoltage Mode (HVM) (capacitance fixed at fifty microfarads) and LowVoltage Mode (LVM) (with a capacitance range from 25 to 3,175microfarads).

The ECM 600 signal generator has a control knob that permits theadjustment of the amplitude of the set charging voltage applied to theinternal capacitors from 50 to 500 volts in LVM and from 0.05 to 2.5 kVin the HVM. The amplitude of the electrical signal is shown on a displayincorporated into the ECM 600 signal generator. This device furtherincludes a plurality of push button switches for controlling pulselength, in the Low VM mode, by a simultaneous combination of resistorsparallel to the output and a bank of seven selectable additivecapacitors.

The ECM 600 signal generator also includes a single automatic charge andpulse push button. This button may be depressed to initiate bothcharging of the internal capacitors to the set voltage and to deliver apulse to the outside electrodes in an automatic cycle that takes lessthan five seconds. The manual button may be sequentially pressed torepeatedly apply the predetermined electric field.

Preferably, the therapeutic method of the invention utilizes a squarewave pulse electroporation system. For example, the ElectroSquarePorator(T820), also available from GENETRONICS, INC., can be used.

Square wave electroporation systems deliver controlled electric pulsesthat rise quickly o to a set voltage, stay at that level for a setlength of time (pulse length), and then quickly drop to zero. This typeof system yields better transformation efficiency for theelectroporation of plant protoplast and mammalian cell lines than anexponential decay system.

The ElectroSquarePorator (T820) is the first commercially availablesquare wave electroporation system capable of generating up to 3000volts. The pulse length can be adjusted from 5 μsec to 99 msec. Thesquare wave electroporation pulses have a gentler effect on the cellswhich results in higher cell viability.

The T820 ElectroSquarePorator is active in both the High Voltage Mode(HVM) (100-3000 volts) and the Low Voltage Mode (LVM)(50-500 volts). Thepulse length for LVM is about 0.3 to 99 msec and for HVM, 5 to 99 μsec.The T820 has multiple pulsing capability from about 1 to 99 pulses.

Mir and others have used square wave pulses for electrochemotherapy,which allows the insertion of chemotherapeutic agents into canceroustumors. Mice were injected with a low dose of bleomycin. The canceroustumors were then electroporated resulting in the reduction or completeremission of the tumors (Mir, L. M., Eur. J. Cancer, 27(1):68, 1991).

Saunders has compared the square wave with exponential decay pulses inthe electroporation of plant protoplas. Square wave electroporationproduced higher transformation efficiency than the exponential decaypulses. He also reported that the optimization of electroporationparameters is much easier with square wave pulses since sufficienttransformation efficiency can be produced over a larger range ofvoltages (Saunders, Guide to Electroporation and Electrofusion,pp.227-247, 1991).

The therapeutic method of the invention includes electrotherapy, alsoreferred to herein as electroporation-mediated therapy, using theapparatus of the invention for the delivery of macromolecules to a cellor tissue. As described earlier, the term “macromolecule” or “molecule”as used herein refers to drugs (e.g., chemotherapeutic agents), nucleicacids (e.g., polynucleotides), peptides and polypeptides, includingantibodies. The term polynucleotides include DNA, cDNA and RNAsequences.

Drugs contemplated for use in the method of the invention are typicallychemotherapeutic agents having an antitumor or cytotoxic effect. Suchdrugs or agents include bleomycin, neocarcinostatin, suramin, andcisplatin. Other chemotherapeutic agents will be known to those of skillin the art (see for example The Merck Index). The chemical compositionof the agent will dictate the most appropriate time to administer theagent in relation to the administration of the electric pulse. Forexample, while not wanting to be bound by a particular theory, it isbelieved that a drug having a low isoelectric point (e.g.,neocarcinostatin, IEP=3.78), would likely be more effective ifadministered post-electroporation in order to avoid electrostaticinteraction of the highly charged drug within the field. Further, suchdrugs as bleomycin, which have a very negative log P, (P being thepartition coefficient between octanol and water), are very large in size(MW=1400), and are hydrophilic, thereby associating closely with thelipid membrane, diffuse very slowly into a tumor cell and are typicallyadministered prior to or substantially simultaneous with the electricpulse. Electroporation facilitates entry of bleomycin or other similardrugs into the tumor cell by creating pores in the cell membrane.

It may be desirable to modulate the expression of a gene in a cell bythe introduction of a molecule by the method of the invention. The term“modulate” envisions the suppression of expression of a gene when it isover-expressed, or augmentation of expression when it isunder-expressed. Where a cell proliferative disorder is associated withthe expression of a gene, nucleic add sequences that interfere with thegene's expression at the translational level can be used. This approachutilizes, for example, antisense nucleic acid, ribozymes, or triplexagents to block transcription or translation of a specific mRNA, eitherby masking that mRNA with an antisense nucleic acid or triplex agent, orby cleaving it with a ribozyme.

Antisense nucleic acids are DNA or RNA molecules that are complementaryto at least a portion of a specific mRNA molecule (Weintraub, ScientificAmerican, 262:40, 1990). In the cell, the antisense nucleic acidshybridize to the corresponding mRNA, forming a double-stranded molecule.The antisense nucleic acids interfere with the translation of the mRNA,since the cell will not translate a mRNA that is double-stranded.Antisense oligomers of about 15 nucleotides are preferred, since theyare easily synthesized and are less likely to cause problems than largermolecules when introduced into the target cell. The use of antisensemethods to inhibit the in vitro translation of genes is well known inthe art (Marcus-Sakura, Anal.Biochem., 172:289, 1988).

Use of an oligonucleotide to stall transcription is known as the triplexstrategy since the oligomer winds around double-helical DNA, forming athree-strand helix. Therefore, these triplex compounds can be designedto recognize a unique site on a chosen gene (Maher, et al., AntisenseRes. and Dev., 1(3:227, 1991; Helene, C., Anticancer Drug Design,6(6):569, 1991).

Ribozymes are RNA molecules possessing the ability to specificallycleave other single-stranded RNA in a manner analogous to DNArestriction endonucleases. Through the modification of nucleotidesequences which encode these RNAs, it is possible to engineer moleculesthat recognize specific nucleotide sequences in an RNA molecule andcleave it (Cech, J.Amer.Med. Assn., 260:3030, 1988). A major advantageof this approach is that, because they are sequence-specific, only mRNAswith particular sequences are inactivated.

There are two basic types of ribozymes namely, tetrahymena-type(Hasselhoff, Nature, 334:585, 1988) and “hammerhead”-type.Tetrahymena-type ribozymes recognize sequences which are four bases inlength, while “hammerhead”-type ribozymes recognize base sequences 11-18bases in length. The longer the recognition sequence, the greater thelikelihood that the sequence will occur exclusively in the target mRNAspecies. Consequently, hammerhead-type ribozymes are preferable totetrahymena-type ribozymes for inactivating a specific mRNA species and18-based recognition sequences are preferable to shorter recognitionsequences.

The present invention also provides gene therapy for the treatment ofcell proliferative or immunologic disorders mediated by a particulargene or absence thereof. Such therapy would achieve its therapeuticeffect by introduction of a specific sense or antisense polynucleotideinto cells having the disorder. Delivery of polynucleotides can beachieved using a recombinant expression vector such as a chimeric virus,or the polynucleotide can be delivered as “naked” DNA for example.

Various viral vectors which can be utilized for gene therapy as taughtherein include adenovirus, herpes virus, vaccinia, or, preferably, anRNA virus such as a retrovirus. Preferably, the retroviral vector is aderivative of a murine or avian retrovirus. Examples of retroviralvectors in which a single foreign gene can be inserted include, but arenot limited to: Moloney murine leukemia virus (MoMuLV), Harvey murinesarcoma virus (HaMuSV), murine mammary tumor virus (MuMTV), and RousSarcoma Virus (RSV). When the subject is a human, a vector such as thegibbon ape leukemia virus (GaLV) can be utilized. A number of additionalretroviral vectors can incorporate multiple genes. All of these vectorscan transfer or incorporate a gene for a selectable marker so thattransduced cells can be identified and generated.

Therapeutic peptides or polypeptides may also be included in thetherapeutic method of the invention. For example, immunomodulatoryagents and other biological response modifiers can be administered forincorporation by a cell. The term “biological response modifiers” ismeant to encompass substances which are involved in modifying the immuneresponse. Examples of immune response modifiers include such compoundsas lymphokines. Lymphokines include tumor necrosis factor, interleukins1, 2, and 3, lymphotoxin, macrophage activating factor, migrationinhibition factor, colony stimulating factor, and alpha-interferon,beta-interferon, and gamma-interferon and their subtypes.

Also included are polynucleotides which encode metabolic enzymes andproteins, including antiangiogenesis compounds, e.g., Factor VIII orFactor IX.

The macromolecule of the invention also includes antibody molecules. Theterm “antibody” as used herein is meant to include intact molecules aswell as fragments thereof, such as Fab and F(ab′)₂.

Administration of a drug, polynucleotide or polypeptide, in the methodof the invention can be, for example, parenterally by injection, rapidinfusion, nasopharyngeal absorption, dermal absorption, and orally. Inthe case of a tumor, for example, a chemotherapeutic or other agent canbe administered locally, systemically or directly injected into thetumor. When a drug, for example, is administered directly into thetumor, it is advantageous to inject the drug in a “fanning” manner. Theterm “fanning” refers to administering the drug by changing thedirection of the needle as the drug is being injected or by multipleinjections in multiple directions like opening up of a hand fan, ratherthan as a bolus, in order to provide a greater distribution of drugthroughout the tumor. As compared with a volume that is typically usedin the art, it is desirable to increase the volume of thedrug-containing solution, when the drug is administered (e.g., injected)intratumorally, in order to insure adequate distribution of the drugthroughout the tumor. For example, in the EXAMPLES herein, one of skillin the art typically injects 50 μl of drug-containing solution, however,the results are greatly improved by increasing the volume to 150 μl.Preferably, the injection should be done very slowly and at theperiphery rather than at the center of the tumor where the intertitalpressure is very high.

Preferably, the molecule is administered substantially contemporaneouslywith the electroporation treatment. The term “substantiallycontemporaneously” means that the molecule and the electroporationtreatment are administered reasonably close together with respect totime. The administration of the molecule or therapeutic agent can at anyinterval, depending upon such factors, for example, as the nature of thetumor, the condition of the patient, the size and chemicalcharacteristics of the molecule and half-life of the molecule.

Preparations for parenteral administration include sterile or aqueous ornon-aqueous solutions, suspensions, and emulsions. Examples ofnon-aqueous solvents are propylene glycol, polyethylene glycol,vegetable oils such as olive oil, and injectable organic esters such asethyl oleate. Carriers for occlusive dressings can be used to increaseski permeability and enhance antigen absorption. Liquid dosage forms fororal administration may generally comprise a liposome solutioncontaining the liquid dosage form. Suitable forms for suspending theliposomes include emulsions, suspensions, solutions, syrups, and elixirscontaining inert diluents commonly used in the art, such as purifiedwater. Besides the inert diluents, such compositions can also includeadjuvants, wetting agents, emulsifying and suspending agents. Further,vasoconstrictor agents can be used to keep the therapeutic agentlocalized prior to pulsing.

Any cell can be treated by the method of the invention. The illustrativeexamples provided herein demonstrate the use of the method of theinvention for the treatment of tumor cells, e.g., pancreas and lung.Other cell proliferative disorders are amenable to treatment by theelectroporation method of the invention. The term “cell proliferativedisorder” denotes malignant as well as non-malignant cell populationswhich often appear to differ from the surrounding tissue bothmorphologically and genotypically. Malignant cells (i.e., tumors orcancer) develop as a result of a multi-step process. The method of theinvention is useful in treating malignancies or other disorders of thevarious organ systems, particularly, for example, cells in the pancreasand lung, and also including cells of heart, kidney, muscle, breast,colon, prostate, thymus, testis, and ovary. Preferably the subject ishuman.

The following examples are intended to illustrate but not limit theinvention. While they are typical of those that might be used, otherprocedures known to those skilled in the art may alternatively be used.

EXAMPLES

The following examples illustrate the use of electrochemotherapy (ECT)of a poorly differentiated human pancreatic tumor (Panc-3) xenograftedsubcutaneously on the left flank of nude mice. The single treatmentprocedure involved injection of bleomycin (0.5 units in 0.15 ml saline)intratumorally, using fanning, as described herein followed byapplication of six square wave electrical pulses, ten minutes later,using proprietary needle array electrodes arranged along thecircumference of a circle 1 cm in diameter. Needle array of variablediameters (e.g., 0.5 cm, 0.75 cm and 1.5 cm can also be used toaccommodate tumors of various sizes. Stoppers of various heights can beinserted at the center of the array to make the penetration depth of theneedles into the tumor variable. A built-in mechanism allowed switchingof electrodes for maximum coverage of the tumor by the pulsed field. Theelectrical parameters were: 1300 V/cm and 6×99 μs pulses spaced at 1 secinterval.

Results showed severe necrosis and edema in nearly all the mice at thetreatment site. While there was a substantial reduction in the tumorvolume (after a slight initial increase due to edema) of the mice in thetreated group (D+E+; D=Drug, E=Electrical field), those in the controlgroup (D+E−) increased dramatically. Nearly complete tumor regressionwas observed in 90% of the mice treated by ECT after 28 days. Noresponse was seen in 10% of the mice. A complete regression with nopalpable tumor has been observed in 60% of the cases 77 days after theinitial treatment. However, there was tumor regrowth in 20% of the mice35 days after treatment but at a much slower growth rate compared to thecontrol. This observation has been linked to incomplete treatment oflarge primary tumors where the needle depth was lower than the Zdimension of the tumor. Histological analysis of tumor samples showednecrotic tumor cell ghosts in D+E+ group compared to a mixture of viableand necrotic cells in D+E− group. Preliminary studies with humannon-small cell lung cancer (NSCLC) tumors xenografted onto nude micehave also shown very encouraging results with ECT treatment withbleomycin.

Example 1

The tumor cell line Panc-3, a poorly differentiated adenocarcinoma cellline of the pancreas, was supplied by AntiCancer, Inc., San Diego. ForECT experiments, tissue taken from the stock mice, where the tumor finewas maintained, was thawed and cut into very small pieces about 1 mmeach, and 8-10 pieces were surgically xenografted in a subcutaneous sacmade in left flank of nude mice, and then closed with 6.0 surgicalsuture. After the average tumor size reached about 5 mm, mice withpalpable tumors were divided randomly, 10 mice for control group (D+E−;D=Drug, E=Electric field) and 10 mice for ECT treatment namely bleomycininjection followed by pulsing (D+E+) from a BTX Square Wave T820Generator. The tumor dimensions were measured and the tumor volumecalculated using the formula:

(II/6)×a×b×c

where a, b, and c are, respectively, the length, width and thickness ofthe tumor. 0.5 units Bleomycin (Sigma Chemicals) was dissolved in 0.15ml of 0.9% NaCl and was injected in each mice intratumorally by fanningfor both the control (D+E−) and the treated (D+E+) groups. Ten minutesafter the injection, each mouse in the D+E+ group was pulsed from a BTXT820 square wave electroporator with a set of needle array electrodes asdescribed in the present invention. Electrical parameters used were asfollows: field strength 1300 V/cm, 6 pulses of 99 μs each, at 1 secinterval.

The mice were monitored every day for mortality and any signs of adiseased state were noted. The tumor dimensions were measured at regularintervals and tumor growth regression/progression monitored. Another setof nude mice with xenografts of non-small cell lung cancer line was alsotreated by the same procedure as for the Panc-3 tumors.

FIGS. 10a and 10 b show the analysis of the tumor volume determined overa 43 day period after ECT using bleomycin for the Panc-3 tumors. Therewas a dramatic difference In between the untreated and treated mice interms of tumor volume. There was essentially no detectable tumor afterapproximately 24 days of treatment. The results of FIG. 10 are alsosummarized in Table 1 below. An illustration of the actual regression ofthe tumor is shown in FIG. 11.

TABLE 1 ELECTROCHEMOTHERAPY OF PANC-3 TUMORS IN NUDE MICE Tumor Daysafter volume Tumor volume Tumor volume Tumor volume treatment (mm³) C1(mm³) C2 (mm³) T1 (mm³) T2 0 138.746 148.94 123.11 178.37 1 206.979179.82 210.95 252.72 8 394.786 451.787 104.55 211.11 15 557.349 798.919113.21 226.966 18 939.582 881.752 161.73 246.91 24 1391.057 1406.9841.56 47.2228 28 1628.631 1474.21 0 0 35 2619.765 2330.31 0 0 382908.912 2333.967 0 0 43 3708.571 5381.759 0 0 Cell Line: poorlydifferentiated human pancreatic tumor (panc3) Mouse model: nude mouseTransplant: subcutaneous xenograft Control mice: C1 and C2 Treated mice:T1 and T2

The Panc-3 experiment was repeated using a non-small cell lung cancercell line (NSCLC), 177 (AntiCancer, San Diego, Calif.) The results weresimilar to that found with bleomycin and Panc-3 as shown in FIGS. 12aand 12 b. In one experiment, a tumor that had recurred was retreated atday 27 (FIG. 13) and after 7 days, there was no evidence of tumor.

The Panc-3 and NSCLC models were utilized with the drug neocarcinostatin(NCS) following the same procedures as outlined above. As shown in FIG.14a and 14 b, pre-pulse dosing with NCS in a manner similar to that usedfor the bleomycin studies, was not effective in reducing tumor size atall. It was believed that due to the low isoelectric point of NCS,electrostatic interaction prevented the drug from entering the tumorcell. Therefore, the experiment was repeated by pulsing first andinjecting NCS post-pulse.

FIG. 14c shows the initial tumor volume (I) as compared to the finaltumor volume (F) at day 13 for 7 mice treated (Mouse ID 1-7). In severalof the mice (ID 1, 2, 4, and 7), an increase in tumor volume wasobserved, but appeared to be due to edema. However, as shown in FIG.14d, when a separate group of 5 mice were examined at day 23, all miceshowed a marked reduction in tumor volume.

A comparison of FIGS. 14a and b with 14 c and d indicated thatpost-pulse with NCS was more effective than pre-pulse administration forNCS.

Summary

The present Examples illustrate that a poorly differentiated Pancreaticcancer (Panc-3) and Non-small cell lung cancer (NSCLC) xenograftedsubcutaneously onto nude mice can be effectively treated by theelectrochemotherapy protocol using bleomycin or NCS and needle arrayelectrodes. Other similar chemotherapeutic agents can also be effectiveusing the method of the invention.

The results show a complete regression of Panc-3 tumors was achieved in60% of the treated group with no palpable tumor seen even 77 days afterthe single treatment. Partial regression (80% reduction in tumor volume)was observed in 30% of cases, while only 10% did not respond (Table 2).

Histological studies clearly showed severe necrosis of the tumor regionfor the group subjected to ECT whereas no necrosis was apparent in thecontrol group. Intratumoral drug injection with larger volume ofbleomycin, combined with farming to maximize uniform drug distributionthroughout the tumor volume, was found to be very effective as comparedto the conventional mode of injecting the drug prior to pulsing.

TABLE 2 Electrochemotherapy of Panc-3 with Bleomycin Days aftertreatment 28 35 57 77 CR (100%) 6 6 6 6 PR (80%) 3 NR (%) 1 1 1 1 Death 2* Tumor regrowth 2 Retreatment 2 Histology 1 Number of mice treated:10 CR: Complete Regression PR: Partial Regression NR: No Response *1mice died after retreatment 1 mice died after 64 days survival

Although the invention has been described with reference to thepresently preferred embodiment, it should be understood that variousmodifications can be made without departing from the spirit of theinvention. Accordingly, the invention is limited only by the followingclaims.

What is claimed is:
 1. An electrode apparatus for the application ofelectric fields to a selected portion of a living body, comprising; asupport member; an array of at least two pars of electrodes mounted onsaid support member in spaced relation to one another, the at least twopairs of electrodes spaced in a substantially rectangular array, and atleast one of said electrodes having a needle configuration forpenetrating tissue for in vivo electroporation of cells of the tissue;an electric pulse generator; and an electrical circuit connected to saidelectrodes and including switching means for selectively connecting atleast two opposing pairs of said electrodes of opposite polarity to saidpulse generator to permit delivery to alternate opposed pairs of saidelectrodes, but not all electrodes, proportionate to the distancebetween said electrodes for electroporation of cells within the electricfield generated by said electrodes.
 2. An apparatus according to claim 1wherein said electrode having a needle configuration is a cannula forthe introduction of molecules into said tissue.
 3. An apparatusaccording to claim 1 wherein said support member comprises a hub andsaid electrodes are in a circular array supported on said hub.
 4. Anapparatus according to claim 3 wherein said switching means comprises aswitch assembly including a rotary switch selectively positionable forconnecting opposite pairs of electrodes to said pulse generator.
 5. Anapparatus according to claim 4 wherein said rotary switch comprisesmeans for connecting each electrode in said pair to one of the twoelectrodes closest to each electrode of said pair.
 6. An apparatusaccording to claim 5 wherein said pairs of electrodes define corners ofa rectangle.
 7. An apparatus according to claim 3 wherein said pairs ofelectrodes define corners of a rectangle.
 8. An apparatus according toclaim 1 wherein all said electrodes are needle electrodes.
 9. Anapparatus according to claim 8 wherein said pairs of electrodes definecorners of a rectangle.
 10. An apparatus according to claim 8 whereinsaid switching means comprises means for connecting each electrode insaid pair to one of the two electrodes closest to each electrode of saidpair.
 11. An apparatus according to claim 10 wherein said pairs ofelectrodes define corners of a rectangle.
 12. An apparatus according toclaim 1 wherein said pairs of electrodes are positioned to definecorners of a rectangle.
 13. An apparatus according to claim 12 wherein:said electrodes are needle electrodes mounted on said support memberwithin a circular array; and said switching means comprises means forconnecting each electrode in said pair to one of the two electrodesclosest to each electrode of said pair.
 14. An apparatus according toclaim 1 wherein said array of electrodes comprises a plurality of needleelectrodes in at least a first row and a plurality of needle electrodesin at least a second row; and said switching means operative forselectively connecting multiple needle electrodes in said first row in afirst polarity and multiple needle electrodes in said second row in asecond polarity.
 15. An apparatus according to claim 14 wherein saidmultiple needle electrodes comprise at least two electrodes in each ofsaid first and second rows.
 16. A needle electrode assembly for theapplication of electric fields to a selected portion of a living body,comprising: an array of multiple electrodes disposed in spaced relationto one another, at least a plurality of said electrodes comprisingneedles arranged to be connected in at least two opposed pairs in asubstantially rectangular configuration; an electric pulse generator;and an electrical circuit including switching means connected to saidelectrodes for selectively connecting the at least two opposing pairs ofsaid electrodes to said pulse generator to permit delivery ofelectroporating voltages to the at least two pairs of said electrodes,but not all electrodes, at the same time and proportionate to thedistance between said electrodes for electroporation of cells in tissuewith the electric field generated by said electrodes, at least oneelectrode of a pair of said electrodes connectable with an adjacentelectrode to define one of a second pair of electrodes.
 17. An apparatusaccording to claim 16 wherein at least one of said needle electrodes isa cannula for the introduction of molecules into tissue.
 18. Anapparatus according to claim 16 wherein said electrodes are needlesdisposed in a circular array.
 19. An apparatus according to claim 18wherein said switching means comprises a switch assembly including arotary switch selectively positionable for connecting opposite pairs ofelectrodes to said pulse generator.
 20. An apparatus according to claim16 wherein said switching means comprises a switch assembly including arotary switch selectively positionable for connecting opposite pairs ofelectrodes to said pulse generator.
 21. An apparatus according to claim20 wherein said switching means is connectable for selectively changingthe polarity of opposing pairs of said electrodes.
 22. An apparatusaccording to claim 20 wherein at least one of said needle electrodes isa cannula for the introduction of molecules into tissue.
 23. Anapparatus according to claim 16 further comprising a pulse generatorhaving a field strength of from about 0.05 kV/cm to about 20 kV/cm. 24.A needle electrode assembly for the application of electric fields to aselected portion of a living body, comprising: a support member; anarray of multiple needle electrodes mounted on said support structure inspaced relation to one another, at least a plurality of said electrodescomprising multiple needles arranged in a rectangular configuration inat least first and second parallel rows; an electric pulse generator;and an electrical circuit including switching means connected to saidelectrodes for selectively connecting at least a first plurality of saidelectrodes in one of said first and second rows in a first polarity andat least a second plurality of electrodes in the other of said first andsecond rows in an opposite polarity to said pulse generator to permitdelivery of electroporating voltages to said first plurality of saidelectrodes and second plurality of said electrodes at the same time andproportionate to the distance between said electrodes forelectroporation of cells in tissue within the electric field generatedby said electrodes.
 25. A needle electrode assembly for the applicationof electric fields to a selected portion of a living body, comprising: asupport member; an array of multiple needle electrodes mounted an saidsupport member in spaced relation to one another, at least a pluralityof said electrodes comprising multiple needles arranged in asubstantially rectangular configuration in at least first and secondparallel rows; an electric pulse generator; and an electrical circuitincluding switching means connected to said electrodes for selectivelyconnecting at least a first plurality of said electrodes in one of saidfirst and second rows in a first polarity and at least a secondplurality of electrodes in the other of said first and second rows in anopposite polarity to said pulse generator to permit delivery ofelectroporating voltages to said electrodes and second plurality of saidelectrodes, but not all electrodes, at the same time and proportionateto the distance between said electrodes for electroporation of cells intissue within the electric field generated by said electrodes.
 26. Anapparatus according to claim 25 wherein said multiple needle electrodescomprise at least two electrodes in each of said first and second rows.27. An apparatus according to claim 25 wherein said switching meanscomprises means for connecting each electrode in one row to at least oneof the electrodes in the other row.